The invention relates to sensors for rotatable shafts. More specifically, the invention relates to sensors that can advantageously be used for speed and torque measurements for rotatable shafts.
Sensing operational characteristics of rotatable shafts such as speed and torque has many applications. For example, sensors are often required to determine engine drive shaft rotation speeds. Optical rotation sensors are known and have the advantage of being less sensitive to electromagnetic interference, noise and harsh environmental conditions such as high temperature, pressure and vibration. Unfortunately, known optical sensors are somewhat limited in use because other environmental conditions such as lubricating fluids and combustion by-products can deteriorate the effectiveness of optical sensors that utilize light near the visible spectrum.
In addition, it is expected that next generation aircraft will make substantial use of composite materials, such as carbon-carbon composites, for drive shafts and the like. Therefore, the need exists for a rotation sensor that can be easily used with shafts made of such composite type materials with performance that is not degraded by the aforementioned environmental conditions.